1. Field of the Invention
The present invention relates to an information processing apparatus which manages document files, a printing apparatus which acquires a document file to be printed and prints it, a control method therefor, an information processing system having these apparatuses, and a program.
2. Description of the Related Art
A printing system which executes printing by transmitting data via a network from an information processing apparatus such as a personal computer to an image output apparatus (to be simply referred to as a printer hereinafter) such as a page printer or MFP (Multi Function Peripheral) has conventionally been popular.
Generally in the printing system, when the number of queued print jobs or the processing amount (e.g., the number of output copies) is large in printing, a print job is temporarily stored (accumulated) in a nonvolatile memory such as a hard disk drive (HDD) in the printer, and then output.
In the printing system, if the HDD of the printer is stolen or the printer is illicitly accessed, it becomes difficult to ensure the security of a print job stored in the HDD.
To solve this problem, there is a technique of encrypting all print jobs to be saved in an HDD, then accumulating them, and at the start of actual printing, decrypting them in a nonvolatile memory (to be referred to as a RAM hereinafter) and printing (Japanese Patent Laid-Open No. 2001-306273). According to Japanese Patent Laid-Open No. 2001-306273, security can be maintained even when the printer stops for a long time owing to a trouble such as a paper jam or the absence of toner.
There is also proposed a technique of ensuring the security of a network which connects a personal computer and printer. More specifically, the personal computer encrypts a print job (encrypts not the communication channel but the print job itself), and then transmits it to the printer. The printer decrypts the received encrypted print job (the user inputs a password via a user interface), and prints. This printing method will be called encrypted printing.
In general, however, most PDL files (e.g., a PostScript file) and electronic document files cannot be encrypted for each page according to the specifications. In printing, not each print page but an entire electronic document file or PDL needs to be decrypted. To execute encrypted printing of an electronic document file or PDL while maintaining security according to the conventional technique, data corresponding to the entire electronic document file or PDL needs to be decrypted in the RAM. The printer requires a large-capacity RAM.
In practice, no large-capacity RAM can be mounted in the printer. Thus, if such a print job is input, the printer cannot process it, resulting in an error. To avoid this, such a print job needs to be temporarily saved in not the RAM but HDD of the printer.
In this case, no electronic document or PDL can be deleted from the HDD of the printer till the end of processing a print job, and decrypted print data remains saved in the HDD. If the printer stops owing to a trouble such as a jam, the decrypted print data is left in the HDD of the printer, failing to ensure the security of the print data.
That is, encrypted printing according to the conventional technique cannot achieve both execution of a print job and ensuring of security.